Rod reducer ratchet lock-out mechanism

ABSTRACT

Spinal surgical procedures can benefit from a rod reduction instrument with a ratchet lock-out mechanism. The instrument can include an inner shaft, an outer housing and a ratchet mechanism. The inner shaft can include a threaded proximal portion and a distal end that includes a plurality of engagement members adapted to receive a pedicle screw. The outer housing can be slidably received over the inner shaft, and include a top sleeve and a bottom sleeve. The top sleeve can include the ratchet mechanism to selectively engage the threaded proximal portion of the inner shaft and the bottom sleeve can engage a connecting rod. The ratchet mechanism can include an engagement feature to selectively engage the threaded proximal portion of the inner shaft, and a locking mechanism to selectively lock the engagement feature of the ratchet mechanism against the threaded proximal portion of the inner shaft.

CLAIM OF PRIORITY

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/641,500, filed on Mar. 12, 2018, the benefit ofpriority of which is claimed hereby, and which is incorporated byreference herein in its entirety.

TECHNICAL FIELD

The present application relates to spinal fusion procedures involvinguse of rod reduction instruments to assist in securing connecting rodsin pedicle screw implants to immobilize one or more vertebrae.

BACKGROUND

A common surgical procedure to correct deformities in the spine involvesstabilizing affected vertebral bodies with interbody implants, pediclescrews and connecting rods. The interbody implants are used to replacedisc material between the affected vertebral bodies, and promote honeyfusion between the vertebrae. The pedicle screws and connecting rods areused to stabilize the affected portion of the spine to allow fusion tooccur. The portion of the procedure involving rod reduction instrumentsinvolves implanting pedicle screws bilaterally in affected vertebralbodies and then connecting the pedicle screw implants with stiff,usually metal, connecting rods to secure the vertebrae in a desiredorientation. Often a surgeon is attempting to restore some sort ofnatural curvature or realign a displaced vertebra (spondylosis) It isnot uncommon during these procedures for a surgeon to utilize aninstrument designed to assist in leveraging a connecting rod into apedicle screw to restore alignment, these instruments are commonlyreferred to as rod reduction instruments. Rod reduction may be necessarydue to curvature correction or the degree of misalignment (e.g., to pulla vertebra back into alignment).

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1A is an isometric view of a rod reduction instrument, inaccordance with an example embodiment.

FIG. 1B is an exploded isometric view of a rod reduction instrument, inaccordance with an example embodiment.

FIG. 2 is an exploded isometric view of an upper section of a rodreduction instrument, in accordance with an example embodiment.

FIGS. 3A-3J are diagrams and drawings of a ratchet mechanism used in arod reduction instrument, in accordance an example embodiment.

FIG. 4 is an isometric view of a rod reduction instrument, in accordancewith an example embodiment.

FIG. 5 is an exploded isometric view of an upper section of a rodreduction instrument, in accordance with an example embodiment.

FIGS. 6A-6J are diagrams and drawings of a ratchet mechanism used in arod reduction instrument, in accordance an example embodiment.

FIG. 7 is a flowchart illustrating a method for using a rod reductioninstrument, in accordance an example embodiment.

DETAILED DESCRIPTION

The instrument discussed below can be used to quickly and efficientlyreduce connecting rods during spinal fusion procedures utilizing pediclescrews and connecting rods. The inventors have recognized that spinalsurgeons need rod reduction instruments that can quickly engageconnecting rods, provide mechanical advantage when needed, and havemechanical mechanisms to ensure ease of removal at completion of theprocedure. Rod reduction instruments can utilize threaded shafts toprovide mechanical advantage to reduce connecting rods through rotationof an instrument handle, such as a t-handle. However, reductioninstruments that solely utilize threaded reduction can slow down spinalprocedures and require too much manipulation to first engage the rod.Ratchet mechanisms can be utilized to reduce the time and effort to makeinitial engagement of a connecting rod, but ratchet mechanisms can jamduring use and cause difficulties in completing a procedure. In extremecases, jammed instruments can require cutting the connecting rod andremoving the pedicle screw. The current inventors have developed variousratchet lock-out mechanisms for use in rod reduction instruments tosolve the problem of jammed instruments and still provide all thebenefits of instruments with ratcheting capabilities.

Rod reduction instruments are typically provided as part of a fixationsystem that includes implants (pedicle screws), various lengthconnecting rods, and various instruments for the procedure. Theinstruments can include tools for pedicle targeting, pediclepreparation, screw insertion, rod and closure top insertion, andmanipulation. Manipulation tools include rod reduction instruments, suchas rod rockers and reducers. The instruments discussed herein arevariations of axial reducers, but the ratchet lock-out mechanisms andtechniques could be implemented on other rod reduction instrumentsutilizing a threaded shaft. Commercial examples of axial reducersinclude reduction instruments provided by Zimmer Biomet as part of theVital™ Spinal Fixation System. Commercial examples of rocket reducersinclude reducers provided by Zimmer Biomet as part of the Polaris™ orLineum™ OCT spinal deformity correction systems. Surgical techniqueguides from Zimmer Biomet, for systems such as the Vital™ SpinalFixation System, provide an excellent overview of reduction instrumentuse and interactions with pedicle screw implants and connecting rods.Accordingly, details regarding how these instruments connect with theimplants and operate are not discussed in detail, accept as needed tounder the inventive concepts discussed herein.

FIG. 1A is an isometric view of a rod reduction instrument 100, inaccordance with an example embodiment. Rod reduction instrument 100 caninclude inner sleeve 101 and outer housing 110. The distal end of theinner sleeve 101 can include engagement members 103, which are adaptedto engage a housing on a pedicle screw that receives a connecting rod.The outer housing 110 can include a top sleeve 115 rotationally coupledto a bottom sleeve 111. The top sleeve 115 can include a tool socket 116and a ratchet mechanism 120. The distal end of the bottom sleeve 111 caninclude a rod engagement 112, which in this example is a semi-circularcutout in opposing sides of the distal end. In operation, the outerhousing 110 translates over the inner shaft 101, after the inner shaft101 is coupled to the pedicle screw head via engagement members 103.

The rod reduction instrument 100 is an example of a tower reducer thatincorporates the ratchet lock-out mechanism to enable two differentreduction modes of operation. First, with the ratchet mechanismoperation, the tower reducer operates in a quick on, quick off mode thatcaptures the screw head and engages the rod more quickly. After couplingthe engagement members 103 of the inner sleeve 101 to a head of apedicle screw, the outer housing 110 can slide over the inner sleeve 101until the rod engagement 112 engages the rod. A T-handle or similar toolcan then be attached to the tool socket 116 to rotate the top sleeve 115causing the outer housing 110 to translate further downward reducing therod into the head of the pedicle screw. Threaded reduction using thetool socket 116 is accomplished by an engagement feature of the ratchetmechanism 120 engaging a threaded proximal portion of the inner sleeve101. In an example, the engagement feature can be a threaded portion ofthe ratchet mechanism 120. In other examples, the engagement feature canbe an alternative structure, such as small protrusions (numbs) orcaptured ball bearings.

The ratchet mechanism, discussed in greater detail below, can betemporarily disengaged through activation of a button, which allowssmooth and quick initial engagement of the connecting rod. In sameexamples, the button on the ratchet mechanism 120 needs to be activatedto allow the outer housing 110 to freely translate over the inner sleeve101. In other examples, the ratchet mechanism 120 allows the engagementfeature of skip over the threads on the proximal section of the innersleeve 101 without activation of the button on the ratchet mechanism.

In this example, the ratchet mechanism 120 can be shifted into a fixedor threaded mode of operation, locking out the ratchet mechanism. Asdiscussed in detail below, locking out the ratchet mechanism involvesforcing an engagement feature of the ratchet mechanism into fixedengagement with a threaded portion of the inner sleeve 101. In thisfixed mode, the reducer operates as a threaded reduction instrument,with no rapid translation of the outer housing 110. Accordingly, in thefixed mode the outer housing 110 translates based solely on rotationinput received through the tool socket 116 (or any rotation of the topsleeve 115 portion of the outer housing 110). Shifting the ratchetmechanism 120 of the reduction instrument 100 into fixed mode enables auser to remove the reduction instrument from difficult reductionscenarios, where a ratcheting reduction instrument may not functionproperly due to high reduction forces. For example, because ratchetinginstruments typically rely upon some form of biasing element, such as acoil spring, to keep a threaded member engaged with the threaded innersleeve, in certain situations the coils spring can fail to keep thethreads engaged sufficiently to overcome forces operating on theinstrument. In these situations, a ratcheting only instrument may haveto be removed through extraordinary measures, such as cutting theconnecting rod and removing the pedicle screw. A dual mode ratchetingmechanism with a lock-out capability can avoid such extraordinarymeasures by providing a mechanism to fix engagement of the engagementfeature of the ratchet against the threaded portion of the inner sleeve.In the fixed engagement mode, the reduction instrument can leverage themechanical advantage of the threads to overcome external forces jammingthe instrument.

FIG. 1B is an exploded isometric view of the rod reduction instrument100 introduced above. The exploded view provides an introduction toadditional elements of an example ratcheting mechanism as well as theoverall instrument in accordance with this example. The rod reductioninstrument 100 can include an inner sleeve 101, a threaded proximalportion 102 of the inner sleeve 101, and a plurality of engagementmembers 103 (collectively referenced as engagement members 103). The rodreduction instrument 100 can also include an outer housing that includesa top sleeve 115 that rotates in reference to a bottom sleeve 111. Thetop sleeve 115 is coupled to the bottom sleeve via a thrust washer 118and retaining ring 119. In this example, the ratchet mechanism 120 caninclude a pivot shaft 121, a locking mechanism 130, a lever member 140,and a biasing member 146.

FIG. 2 is an exploded isometric view of an upper section of a rodreduction instrument 100, in accordance with an example embodiment. Inthis example, the top sleeve 115 and the ratchet mechanism 120 of therod reduction instrument 100 are illustrated in additional detail. Theratchet mechanism 120 includes features built into the top sleeve 115,such as a detent bore 122, a button opening 123, a button cutout 124,pivot shaft bores 125, slide lock rails 126, and a transverse shaftopening 127. FIG. 2 also illustrates the top sleeve 115 with a toolsocket 116 and rotational coupling 117. The rotational coupling 117 iswhere the top sleeve 115 is connected to the bottom sleeve 111. Theratchet mechanism 120 also includes a pivot shaft 121, a lockingmechanism 130, a lever member 140, and a biasing member 146. The lockingmechanism 130 can also include a lock detent 136 and a ratchet detent137, which operate to retain the locking mechanism 130 is one of the twomodes (locked or fixed and ratcheting). The lever member 140 can includea ratchet release button 142, a pivot 145, and a bias recess 147. Thepivot 145 can receive the pivot shaft 121, and is where the lever member140 rotates or pivots in ratcheting mode. The biasing member 146operates to bias the lever member 140 into engagement with the threadedproximal portion of the inner sleeve 101. As illustrated in greaterdetail in FIGS. 3A-3J, the biasing member 146 can be a wave washerspring, but can also be a coil spring or other comparable biasingmember. In certain examples, an elastic or elastomeric material could besubstituted for the wave washer spring. The biasing member needs toallow for sufficient travel to clear threaded on the inner shaft, withprovide a balance between thread engagement and ratcheting motion.

The locking mechanism 130 slides on the slide lock rails 126 whenassembled into the ratchet mechanism 120. The detent bore 122 isdesigned to hold a detent ball to engage the lock detent 136 and ratchetdetect 137 when locking mechanism 130 slides between fixed mode andratcheting mode (also referred to as Quick On/Off mode).

FIGS. 3A-3J are diagrams and drawings of a ratchet mechanism used in arod reduction instrument, in accordance an example embodiment. FIG. 3Ais a drawing of a superior surface of an assembled the ratchet mechanism120. In this example, the ratchet mechanism 120 can include buttonopening 123, button cutout 124, pivot shaft bores 125, a lockingmechanism 130, lever member 140, and ratchet release button 142. Thelocking mechanism in this example includes slide lock 132, which is aU-shaped linear slide that is further illustrated in the followingfigures. In this example, the lock detent 136 and ratchet detent 137 areshown on opposing arms of the U-shaped slide lock 132.

FIG. 3B is a drawing of a lateral side of the ratchet mechanism 120. Inthis view, the slide lock 132 is illustrated engaged with one of theslide lock rails 126 along a slide recess 133. The slide lock 132includes a slide recess 133 along the outbound edge of each arm of theU-shaped structure. Also illustrated in this view is the pivot shaft 121within the pivot shaft bore 125. When the ratchet release button 142 ofthe lever member 140 is activated, the lever member 140 pivots on thepivot shaft 121 and the engagement feature 141 disengages from anthreaded portion of the inner shaft 101.

FIGS. 3C-3D are cutaway views of the ratchet mechanism 120 andassociated portions of the inner sleeve 101. In these views, thefollowing ratchet mechanism 120 details are depicted, pivot shaft 121,button opening 123, button cutout 124, slide lock 132, lever member 140,and biasing member 146. In this example, the slide lock 132 includes thetransverse shaft 138, which is the structure of the locking mechanism130 that locks out the ratcheting action of the lever member 140. Inthese views, the lever member 140 is illustrated as including anengagement feature 141 on an inferior side of the proximal portion. Thecutaway demonstrates how the engagement feature 141 engages the proximalthreaded portion 102 of inner sleeve 101. In this example, theengagement feature 141 is a plurality of partial threads that correspondto the proximal threaded portion 102 of the inner sleeve 101. Thecutaway also illustrates how the biasing member 146 biases theengagement feature 141 into engagement with the proximal threadedportion 102. The lever member 140 also includes a locking surface 143and a ratchet cavity 144, which are positioned below the transverseshaft 138 of the slide lock 132. In ratcheting mode, the slide lock 132is positioned as shown and the transverse shaft 138 is opposite theratchet cavity 144, which provides clearance for the lever member 140 topivot without interference from the transverse shaft 138. However, inthe fixed (or locked) mode, the slide lock 132 is shifted proximally,and the transverse shaft 138 is positioned opposite the locking surface143. In the fixed mode, the lever member 140 is prevented from pivotingdue to engagement between the transverse shaft 138 and the lockingsurface 143.

FIGS. 3E-3J are various drawings providing additional detailed views ofthe locking mechanism 130, the lever member 140, and parts of theratchet mechanism 120. FIG. 3E is an isometric view of the pivot shaft121, locking mechanism 130, and lever member 140. In this view, theU-shaped structure of the slide lock 132 is depicted with the sliderecesses 133 along the ends of each arm. FIG. 3F is a superior surfaceview of the locking mechanism 130 and lever member 140. FIG. 3G is aninferior surface view of the locking mechanism 130 and lever member 140.In this view, the engagement feature 141 of the lever member 140 isshown including at least three angled threads in the thread pattern. Inother examples, a different thread pattern can be utilized and theengagement feature 141 can have more or fewer threads. In otherexamples, the engagement feature 141 can include a series of protrusionspositioned to engage the threaded proximal portion 102. In yet otherexamples, the engagement feature 141 can include one or more capturedball bearings positioned to engage the threads in the threaded proximalportion 102, in this example the threads in the threaded proximalportion 102 may be structured to accept the ball bearings. This viewalso includes detent balls 134 and detent springs 135, which assist inholding slide lock 132 in the fixed or ratcheting position. FIG. 3H is alateral view drawing of the locking mechanism 130 and lever member 140.FIG. 3I is an axial view along a longitudinal axis of the rod reductioninstrument of the locking mechanism 130 and the lever member 140. Thisview depicts the U-shaped structure of the slide lock 132 with thec-shaped slide recesses 133 on the outbound end of each leg of the U.The view also depicts the curve of the engagement feature 141 on theinferior side of the proximal portion of the lever member 140. Oppositethe engagement feature 141 is the biasing member 146, which is held inplace by an inferior surface of the slide lock 132. FIG. 3J is a cutawayperspective view of the locking mechanism 130 and lever member 140providing a slightly different perspective on the elements discussedabove.

FIG. 4 is an isometric view of a rod reduction instrument 200, inaccordance with an example embodiment. The rod reduction instrument 200is similar to rod reduction instrument 100 discussed above, but includesa different ratchet lock-out mechanism. The following discussion willprimarily focus on the differences in the ratchet mechanism 220, as therest of the functionality of the rod reduction instrument 200 iscomparable to that of rod reduction instrument 100. As illustrated inFIG. 4, the rod reduction instrument 200 can include an inner shaft 201,engagement members 203, an outer housing 210, and a ratchet mechanism220. The outer housing 210 can include a bottom sleeve 211 and a topsleeve 215. The top sleeve 215 can include a tool socket 216, which canbe used to receive a handle to introduce rotation to the top sleeve 215.The top sleeve 215 can rotate in reference to the bottom sleeve 211around the rotational coupling 217. The bottom sleeve 211 includes a rodengagement 212 on a distal end.

FIG. 5 is an exploded isometric view of an upper section (top sleeve215) of the rod reduction instrument 200, in accordance with an exampleembodiment. In this example, the ratchet mechanism 220 includes pivotshaft 221, button opening 223, button cutout 224, pivot shaft bores 225,ratchet cover 226, locking mechanism 230, and lever member 240. Thelever member 240 is similar to the lever member 140, and includes athreaded inferior surface on a proximal portion and a ratchet releasebutton 242 on a superior surface of a distal portion. The lever member240 receives the pivot shaft 221 between the proximal portion and distalportion. On a superior surface of the proximal portion of the levermember 240 there is a bias recess 247 adapted to receive a biasingmember 246. In this example, the locking mechanism 230 includes a slidelock 232 in the form of a stepped cylindrical shaft. The slide lock 232includes a large diameter section 233, a small diameter section 234, alocking ring 235, and a biasing member 236. As assembled, the slide lock232 is located within a slide lock bore 237 (labeled in FIG. 6J), withthe locking ring 235 securing the slide lock 232 shaft within the bore237.

In this example, the lever member 240 and the biasing member 246 aredropped into the ratchet mechanism 220 through an opening in thesuperior surface, then the ratchet cover 226 is slid into position overthe opening to provide an engagement surface for the biasing member 246to operate against. In an example, edges of the ratchet cover 226 slideinto recesses in the opening in the superior surface of the ratchetmechanism 220. Once the lever member 240 is in position, the pivot shaft221 can be inserted to retain the lever member 240, while allowing thelever member 240 to pivot.

FIGS. 6A-6J are diagrams and drawings of the ratchet mechanism 220 usedin a rod reduction instrument 200, in accordance an example embodiment.FIGS. 6A and 6B are cutaway illustrations of the ratchet mechanism 220as well as depictions of portions of inner shaft 201, top sleeve 215,and bottom sleeve 211. In this example, the thrust washer 218 andretaining ring 219 are illustrated in reference to top sleeve 215 andbottom sleeve 211. Inner shaft 201 includes proximal threaded portion202, which engages with the engagement feature 241 of the lever member240. The biasing member 246 is illustrated urging the lever member 240to pivot on pivot shaft 221 and engage the threaded proximal portion 202of inner shaft 201. The locking surface 243 is also illustrated in thesecutaway views. The locking surface 243 on the lever member 240 is asemi-circular recess along a lateral inferior surface under a portion ofthe ratchet release button 242. As illustrated in other figures, thelarge diameter 233 of the slide lock 232 can be shifted laterally intoengagement with the locking surface 243 to prevent the lever member 240from pivoting and forcing the engagement feature 241 into fixedengagement with the threaded proximal portion 202 of inner shaft 201.With the slide lock 232 engaged, the rod reduction instrument 200operates through rotation of the top sleeve 215 only. The cutaway viewsalso illustrate the structure of the button opening 223 and the buttoncutout 224. The button opening 223 is an opening in the ratchetmechanism 220 that conforms to the outline of the ratchet release button242 of the lever member 240, while the button cutout 224 is a recessedportion around the ratchet release button 242. In some examples, thebutton cutout 224 can include curved sidewalls, and in other examplesthe sidewalls can be straight but angled.

FIG. 6C-6I are various drawings providing additional detailed views ofthe locking mechanism 230 and lever member 240 parts of the ratchetmechanism 220. FIG. 6C is an isometric view of the pivot shaft 221,locking mechanism 230, and lever member 240. In this example, the pivot245 of lever member 240 is identified as the bore in the lever member240 receiving the pivot shaft 221. Other features of the lever member240 illustrated in this example include engagement feature 241, ratchetrelease button 242, locking surface 243, bias recess 247, and the biasmember 246. This example illustrates the relationship between thelocking surface 243 on the lever member 240 and the large diametersection 233 of the stepped cylindrical slide lock 232. While notspecifically identified with a reference number, the slide lock 232includes an enlarged lateral end that operates as a button foractivation of the slide lock 232 of the locking mechanism 230.

FIG. 6D is an inferior side view of the pivot shaft 221, lockingmechanism 230, and lever member 240. In this example, the engagementfeature 241 of the lever member 240 is illustrated as including at leastthree threads running at a shallow angle transverse to a longitudinalaxis of the lever member 240. In some example, more or fewer threads canbe included on the engagement feature 241. The small diameter section234 of the slide lock 232 stepped cylindrical shaft is shown within arecess in the inferior side of the ratchet release button 242 portion ofthe lever member 240. The lock biasing member 236 is illustrated inposition to bias the slide lock 232 into an unlocked position.

FIG. 6E is a superior side view of the pivot shaft 221, lockingmechanism 230, and lever member 240. FIG. 6F is a lateral side view ofthe pivot shaft 221, locking mechanism 230, and lever member 240. Inthis view, the engagement feature 241 is illustrated as including fourpartial threads to engage the threaded proximal portion 202 of the innershaft 201.

FIG. 6G is a medial side view of the pivot shaft 211, locking mechanism230, and lever member 240. In this view, the U-shaped slide lock recess248 in the inferior side of the ratchet release button 242 portion ofthe lever member 240 is shown in relationship to the small diametersection 234 and lock biasing member 236 of the slide lock 232. The slidelock recess 248 provides sufficient clearance to allow the lever member240 to pivot around pivot shaft 221 with the ratchet release button 242is activated, or when ratcheting as the outer housing 210 slides overthe inner shaft 201. FIGS. 6G and 6I are distal and proximal views,respectively, along the longitudinal axis of the rod reductioninstrument 200. FIG. 6I depicts the curved structure of the inferiorsurface of the engagement feature 241 of the lever member 240. Theengagement feature 241 is curved to match the outer curvature of theinner shaft 201.

FIG. 6J is a transverse cutaway view of the ratchet mechanism 220, topsleeve 215, and inner shaft 201. The cutway runs through the steppedcylindrical shaft of the slide lock 232. As illustrated, the lockingring 235 retains the slide lock 232 within the slide lock bore 237 byengaging a cylindrical recess enlarging a section of the slide lock bore237. The cutaway also illustrates how the large diameter section 233 canengage the locking surface 243 on the lever member 240 when the buttonof the slide lock 232 is pushed in compressing the lock biasing member236.

FIG. 7 is a flowchart illustrating a method 700 for using a rodreduction instrument, such as rod reduction instrument 100 or 200discussed above. The method 700 illustrates a common set of operationsutilizing one of the rod reduction instruments discussed above. However,the method 700 does not cover all possible uses of the instruments, theoperations discussed can be done in a different sequence, operationscould be repeated or omitted, as fits the particular scenario of use. Inthis example, the method 700 can include operations such as: coupling toa pedicle screw at 710, selecting Quick On/Off mode at 720, sliding theouter housing into engage with a connecting rod at 730, optionallyattaching a T-handle at 740, reducing the connecting rod at 750, insertclosure into pedicle screw at 760, remove rod reduction instrument at770.

The method 700 can begin at 710 the mode of operation of the instrumentbeing selected. In this example, the Quick On/Off (or ratcheting) modecan be selected by shifting the slide lock, such as slide lock 132, intothe Quick On/Off (distal) position. As discussed above, with theinstrument in the Quick On/Off mode, the ratchet mechanism is free toratchet. In other words, the engagement feature 141 of the lever member140 is not fixed into engagement of the threaded proximal portion 102 ofthe inner sleeve 101. In another example, the user may choose to engagethe threaded operation mode by shifting the slide lock into the Fixed(proximal) position. The operations discussed in method 700 are depictedin a common order of operation, but many of the operations can beshifted into other positions in the method or repeated. For example, themode of operation can be switched at any point during the procedure.

At 720, the method 700 can continue by coupling the rod reductioninstrument to a head of a pedicle screw. For example, engagement members203 of the rod reduction instrument 100 can be placed into engagementwith the head of a pedicle screw. Prior to engaging the pedicle screw, aratchet release button 142 can be engaged and the inner shaft 101 fullyextended into a fully open position. In an example, the instrument caninclude four separate engagement members that engage four vertical slotson the screw head. In other examples, the instrument may only includetwo engagement members that engage either arm of the U-shaped pediclescrew head.

Once the head of the pedicle screw is engaged, the method 700 cancontinue with the instrument free to engage the connecting rod at 730.In this example, the outer housing 110 can slide over the inner sleeve201 to quickly engage the connecting rod through ratcheting. If theinstrument were in the Fixed mode, rotational input to the top sleeve115 would be necessary to translate the outer housing 110 over the innersleeve 101 to engage the connecting rod.

With the connecting rod engaged, the method 700 can optionally continueat 740 with attachment of a T-handle on the tool socket 116 of the topsleeve 115. At 750, the method 700 can continue with the instrumentbeing manipulated to reduce the connecting rod into the head of thepedicle screw. Instrument manipulation can include rotation of theT-handle (or top sleeve 115 if no extra torque is needed), which causestranslation of the outer housing 110. Optionally, the instrument can beshifted into Fixed mode, if rod reduction is particular difficult toensure that the ratchet mechanism 120 does not disengage during threadedreduction.

Once the rod is fully reduced into the pedicle screw, the method 700 cancontinue at 760 with a closure being inserted into the head of thepedicle screw to secure the rod in place. The instrument includes acentral cylindrical passage to allow the closure to be inserted withoutremoving the rod reduction instrument. Once the rod is secure, themethod 700 can continue at 770 with removal of the reduction instrumentfrom the head of the pedicle screw.

The instrument removal operation 770 can optionally include operationssuch as: selecting a mode at 772, rotating the instrument input at 774,activating the ratchet release button 776, and disengaging the pediclescrew at 778. In certain examples, the ratchet mechanism 120 in theQuick On/Off mode may not be able to release the tension on the rodreduction instrument 100. In such a scenario, the instrument can beshifted into Fixed mode through manipulation of the slide lock 132 intothe proximal position. In fixed mode, the top sleeve 215 can be rotatedat 774 to release tension on the outer housing 110 from engagement withthe connecting rod. Once the tension is released, the mode can beshifted back to the Quick On/Off mode, and the ratchet release ratchetrelease button 142 can be activated at 776. Activating the ratchetrelease ratchet release button 142 allows the outer housing 110 to slidein reference to the inner sleeve 101 to open the instrument. Once theinstrument is open, the engagement members 103 can be disengaged fromthe pedicle screw head at 778.

Various Notes & Examples

Each of these non-limiting examples may stand on its own, or may becombined in various permutations or combinations with one or more of theother examples.

Example 1 describes subject matter that can include a rod reductioninstrument. In this example, the rod reduction instrument can include aninner shaft, an outer housing, and ratchet mechanism. The inner shaftcan include a threaded proximal portion and a distal end, the distal endincluding a plurality of engagement members adapted to receive a housingof a pedicle screw. The outer housing can be slidably received over atleast a portion of the inner shaft. The outer housing can also include atop sleeve and a bottom sleeve. In this example, the top sleeve caninclude the ratchet mechanism to selectively engage the threadedproximal portion of the inner shaft, and a distal end of the bottomsleeve adapted to engage a connecting rod. The ratchet mechanism can bedisposed along the top sleeve of the outer housing. In this example, theratchet mechanism can include an engagement feature to selectivelyengage the threaded proximal portion of the inner shaft, and a lockingmechanism to selectively lock the engagement feature of the ratchetmechanism against the threaded proximal portion of the inner shaft.

In Example 2, the subject matter of Example 1 can optionally include thetop sleeve being rotatably coupled to the bottom sleeve and adapted totranslate rotational input into linear translation of the outer housingrelative to the inner shaft.

In Example 3, the subject matter of Example 2 can optionally include theengagement feature of the ratchet mechanism engaging the threadedproximal portion of the inner shaft, upon receiving rotational inputfrom the top sleeve, to linearly translate the outer shaft along alongitudinal axis in relation to the inner shaft.

In Example 4, the subject matter of any one of Examples 1 to 3 canoptionally include the ratchet mechanism having a lever member includinga proximal end and a distal end separated by a pivot.

In Example 5, the subject matter of Example 4 can optionally include theengagement feature of the proximal end of the lever member being adaptedto selectively engage the threaded proximal portion of the inner shaft.

In Example 6, the subject matter of any one of Examples 4 and 5 canoptionally include the distal end of the lever member having a buttonexposed on an external surface of the ratchet mechanism.

In Example 7, the subject matter of any one of Examples 4 to 6 canoptionally include the pivot having a pivot shaft extending intoopposing side walls of the locking mechanism, which enables rotationalmovement of the lever member about the pivot shaft.

In Example 8, the subject matter of Example 7 can optionally include theengagement feature on the proximal portion of the lever memberselectively enaging the threaded proximal surface of the inner shaftthrough the rotational movement of the lever member.

In Example 9, the subject matter of Example 8 can optionally include theratchet mechanism having a biasing member positioned against a superiorsurface of the proximal portion of the lever member opposite theengagement feature to bias the engagement feature against the threadedproximal surface of the inner shaft.

In Example 10, the subject matter of any one of Examples 4 to 9 canoptionally include the locking mechanism having a slide lock disposed onan external surface of the ratchet mechanism adapted to lock the lockingmechanism in a first position and unlock the locking mechanism in asecond position.

In example 11, the subject matter of Example 10 can optionally includethe slide lock being a U-shaped linear slide slidably engage alongopposing sides of the ratchet mechanism, the slide lock translates alonga longitudinal axis of the rod reduction instrument between the firstposition and the second position.

In Example 12, the subject matter of Example 11 can optionally includethe slide lock including a transverse shaft projecting from an inferiorsurface of the slide lock towards the longitudinal axis to engage alocking surface on the lever member.

In Example 13, the subject matter of Example 12 can optionally includethe slide lock being in the first position so the transverse shaftengages the locking surface to prevent the lever member from pivotingthe engagement feature of the lever member away from the threadedproximal portion of the inner shaft.

In Example 14, the subject matter of Example 12 can optionally includethe slide lock being in the second position so the inferior shaft ispositioned over a cavity in the lever member allowing the lever memberto pivot freely within the ratchet mechanism.

In Example 15, the subject matter of Example 10 can optionally includethe slide lock being a stepped cylindrical shaft positioned transversethe lever member and disposed within a bore extending across a portionof a width of the ratchet mechanism.

In Example 16, the subject matter of Example 15 can optionally includethe stepped cylindrical shaft including a large diameter section coupledto a small diameter section, the large diameter section engageable witha locking surface on the lever member to prevent pivoting of the levermember within the ratchet mechanism.

In Example 17, the subject matter of any one of Examples 15 or 16 canoptionally include the slide lock translating within the bore betweenthe first position and the second position.

In Example 18, the subject matter of Example 17 can optionally includethe slide lock being in the first position where a portion of a largerdiameter section of the stepped cylindrical shaft engages a lockingsurface on the lever member to lock-out the ratchet mechanism.

In Example 19, the subject matter of any one of Examples 15 to 18 canoptionally include the locking mechanism including a biasing elementdisposed within the bore to bias the stepped cylindrical shaft into aparticular position, such as the second position.

In Example 20, the subject matter of any one of Examples 15 to 19 canoptionally include the stepped cylindrical shaft being biased into asecond position where the lever member within the ratchet mechanism isfree to pivot the engagement feature away from the threaded proximalportion of the inner shaft allowing the outer shaft to translatedistally over the inner shaft towards the pedicle screw withoutrotational input.

In Example 21, the subject matter of any one of Examples 1 to 20 canoptionally include the engagement feature being selected from a group ofstructures including: threads, numbs, cylindrical protrusions, square orrectangular protrusions, and one or more captured ball bearings.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In the event of inconsistent usages between this document and anydocuments so incorporated by reference, the usage in this documentcontrols.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription as examples or embodiments, with each claim standing on itsown as a separate embodiment, and it is contemplated that suchembodiments can be combined with each other in various combinations orpermutations. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

What is claimed is:
 1. A rod reduction instrument comprising: an innershaft including a threaded proximal portion and a distal end, the distalend including a plurality of engagement members adapted to receive ahousing of a pedicle screw; an outer housing slidably received over atleast a portion of the inner shaft, the outer housing including a topsleeve and a bottom sleeve, the top sleeve including a ratchet mechanismto selectively engage the threaded proximal portion of the inner shaft,and a distal end of the bottom sleeve adapted to engage a connectingrod; a ratchet mechanism disposed along the top sleeve of the outerhousing, the ratchet mechanism including an engagement feature toselectively engage the threaded proximal portion of the inner shaft, theratchet mechanism including a locking mechanism to selectively lock theengagement feature of the ratchet mechanism against the threadedproximal portion of the inner shaft,
 2. The rod reduction instrument ofclaim 1, wherein the top sleeve is rotatably coupled to the bottomsleeve and adapted to translate rotational input into linear translationof the outer housing relative to the inner shaft.
 3. The rod reductioninstrument of claim 2, wherein upon receiving rotational input from thetop sleeve, the engagement feature of the ratchet mechanism engages thethreaded proximal portion of the inner shaft to linearly translate theouter shaft along a longitudinal axis in relation to the inner shaft, 4.The rod reduction instrument of claim 1, wherein the ratchet mechanismincludes a lever member including a proximal end and a distal endseparated by a pivot.
 5. The rod reduction instrument of claim 4,wherein the proximal end of the lever member includes the engagementfeature adapted to selectively engage the threaded proximal portion ofthe inner shaft.
 6. The rod reduction instrument of claim 4, wherein thedistal end of the lever member includes a button exposed on an externalsurface of the ratchet mechanism.
 7. The rod reduction instrument ofclaim 4, wherein the pivot includes a pivot shaft extending intoopposing side walls of the locking mechanism, and the pivot enablesrotational movement of the lever member about the pivot shaft.
 8. Therod reduction instrument of claim 7, wherein the rotational movement ofthe lever member enables the engagement feature on the proximal portionof the lever member to selectively engage the threaded proximal surfaceof the inner shaft.
 9. The rod reduction instrument of claim 8, whereinthe ratchet mechanism includes a biasing member positioned against asuperior surface of the proximal portion of the lever member oppositethe engagement feature to bias the engagement feature against thethreaded proximal surface of the inner shaft.
 10. The rod reductioninstrument of claim 4, wherein the locking mechanism includes a slidelock disposed on an external surface of the ratchet mechanism andadapted to lock the locking mechanism in a first position and unlock thelocking mechanism in a second position.
 11. The rod reduction instrumentof claim 10, wherein the slide lock is a U-shaped linear slide slidablyengage along opposing sides of the ratchet mechanism, the slide locktranslates along a longitudinal axis of the rod reduction instrumentbetween the first position and the second position.
 12. The rodreduction instrument of claim 11, wherein the slide lock includes atransverse shaft projecting from an inferior surface of the slide locktowards the longitudinal axis to engage a locking surface on the levermember.
 13. The rod reduction instrument of claim 12, wherein with theslide lock in the first position the transverse shaft engages thelocking surface to prevent the lever member from pivoting the engagementfeature of the lever member away from the threaded proximalportion ofthe inner shaft.
 14. The rod reduction instrument of claim 12, whereinwith the slide lock in the second position the inferior shaft ispositioned over a cavity in the lever member allowing the lever memberto pivot freely within the ratchet mechanism.
 15. The rod reductioninstrument of claim 10, wherein the slide lock is a stepped cylindricalshaft positioned transverse the lever member and disposed within a boreextending across a portion of a width of the ratchet mechanism.
 16. Therod reduction instrument of claim 15, wherein the stepped cylindricalshaft includes a large diameter section coupled to a small diametersection, the large diameter section engageable with a locking surface onthe lever member to prevent pivoting of the lever member within theratchet mechanism.
 17. The rod reduction instrument of claim 15, whereinthe slide lock translates within the bore between the first position andthe second position.
 18. The rod reduction instrument of claim 17,wherein with the slide lock in the first position a portion of a largerdiameter section of the stepped cylindrical shaft engages a lockingsurface on the lever member to lock-out the ratchet mechanism.
 19. Therod reduction instrument of claim 17, wherein the locking mechanismincludes a biasing element disposed within the bore to bias the steppedcylindrical shaft into the second position.
 20. The rod reductioninstrument of claim 19, wherein when the stepped cylindrical shaft isbiased into the second position the lever member within the ratchetmechanism is free to pivot the engagement feature away from the threadedproximal portion of the inner shaft allowing the outer shaft totranslate distally over the inner shaft towards the pedicle screwwithout rotational input.